Systems, methods and devices for opportunistic networking

ABSTRACT

Opportunistic networking systems can utilize one or multiple bands/channels that are shared with other radio access technologies (RATs) (such as wireless local area networks (WLAN, such as Wi-Fi) and mmWave). An unconventional carrier type (UCT) can be defined to support opportunistic networking in licensed and/or unlicensed spectrum. For example, a primary base station can determine a secondary base station activated for use with user equipment (UE). The primary base station can schedule data to be sent to the UE via the secondary base station. The secondary base station can provide discovery information, reserve a wireless channel, transmit the data and/or release the channel (implicitly, explicitly, or by reservation).

RELATED APPLICATION

This application is a continuation of application U.S. application Ser.No. 14/580,735, filed Dec. 23, 2014, entitled “SYSTEMS, METHODS ANDDEVICES FOR OPPORTUNISTIC NETWORKING” which claims the benefit under 35U.S.C. §119(e) of U.S. Provisional Application No. 61/953,634 filed Mar.14, 2014, entitled “OPPORTUNISTIC NETWORKING SUPPORT FOR LTE CELLULARSYSTEM” both of which are incorporated by reference herein in theirentirety.

TECHNICAL FIELD

The present disclosure relates to wireless transmission systemsincluding systems for sharing wireless spectrum.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an opportunistic networking systemconsistent with embodiments disclosed herein.

FIG. 2 is a block diagram illustrating use cases of an opportunisticnetworking system consistent with embodiments disclosed herein.

FIG. 3 is a diagram of a long term evolution (LTE) frame consistent withembodiments disclosed herein.

FIG. 4 is a diagram illustrating use of an alignment gap to synchronizetransmissions consistent with embodiments disclosed herein.

FIG. 5 is a diagram illustrating use of a preamble within an alignmentgap to synchronize transmissions consistent with embodiments disclosedherein.

FIG. 6 is a diagram illustrating use of a super subframe to synchronizetransmissions consistent with embodiments disclosed herein.

FIG. 7 is a diagram illustrating use of a reduced length subframe tosynchronize transmissions consistent with embodiments disclosed herein.

FIG. 8 is a diagram illustrating use of primary synchronization signalsand/or secondary synchronization signals (PSS/SSS) consistent withembodiments disclosed herein.

FIG. 9 is a diagram illustrating use of periodic transmission ofdiscovery subframes consistent with embodiments disclosed herein.

FIG. 10 is a diagram illustrating unaligned subframes with channelreservation consistent with embodiments disclosed herein.

FIG. 11 is a diagram illustrating unaligned subframes with channelreservation and a discovery subframe consistent with embodimentsdisclosed herein.

FIG. 12 is a process chart illustrating a method for cross-carriertransmission consistent with embodiments disclosed herein.

FIG. 13 is a schematic diagram of a computing system consistent withembodiments disclosed herein.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

A detailed description of systems and methods consistent withembodiments of the present disclosure is provided below. While severalembodiments are described, it should be understood that the disclosureis not limited to any one embodiment, but instead encompasses numerousalternatives, modifications, and equivalents. In addition, whilenumerous specific details are set forth in the following description inorder to provide a thorough understanding of the embodiments disclosedherein, some embodiments can be practiced without some or all of thesedetails. Moreover, for the purpose of clarity, certain technicalmaterial that is known in the related art has not been described indetail in order to avoid unnecessarily obscuring the disclosure.

Techniques, apparatus and methods are disclosed that enableopportunistic networking that utilizes one or multiple bands/channelsthat are used or shared with other radio access technologies (RATs)(such as wireless local area networks (WLAN, such as Wi-Fi) andmillimeter wave (mmWave)). Conventional long term evolution (LTE) usesone or multiple frequency bands that are exclusively assigned to LTE(such as LTE carrier aggregation or New Carrier Type (NCT)). Anunconventional carrier type (UCT) can be defined to supportopportunistic networking in licensed and/or unlicensed spectrum. LTE ina licensed carrier will be referred to as LCT (licensed carrier type).

For example, a primary base station (which can provide a primary carrierand a primary cell (PCell), which can transmit over a primary medium,primary set of frequencies, primary spectrum, primary band, etc.) candetermine a secondary base station (which can provide a secondarycarrier and secondary cell (SCell), which can transmit over a secondarymedium, secondary set of frequencies, secondary spectrum, secondaryband, etc.) to activate for use with user equipment (UE). The primarybase station can schedule data to be sent to the UE via the secondarybase station. The secondary base station can provide discoveryinformation, reserve a wireless channel, transmit the data and/orrelease the channel (implicitly, explicitly, or by reservation).

In one embodiment, fast cell switching is used to opportunistically useavailable spectrum. For example, mmWave technologies may have limitedavailability under unfavorable channel conditions (such as due to thehigh frequency effects). Very fast cell switching can allowopportunistic use of mmWave when available.

In another embodiment, more efficient sharing of a band of frequenciescan be supported by fast switching between dormant (e.g., OFF) andactive (e.g., ON) states. During dormant states, a UCT system willrefrain from transmission to reduce interference to other RATtechnologies using the spectrum. During active states, the UCT systemcan perform downlink (DL) and/or uplink (UL) LTE operations.

In one embodiment, dormant subframes can be used to perform protocols toaid in the sharing of the spectrum. For example, a UCT system canperform listen before talk (LBT) protocols and/or channel reservationtechniques. Once the spectrum is reserved and/or available, the UCT cantransition into an active state.

In another embodiment, a UCT system can reduce periodic transmission ofsignals compared with an LCT system. Instead of typical LCT signals, adiscovery signal and/or synchronization signal can be used. Thediscovery signal can be sent periodically, even when a UCT system is ina dormant state (such as during a dormant subframe).

The demand for wireless broadband data in cellular networks is expectedto increase. By considering user expectations of high data rates alongwith seamless mobility more spectrum can be made available for macrocells and small cells deployment. To support the growing demand ofwireless broadband data, opportunistic use of additional availablespectrum can be used. Such opportunistic network/offloading opportunitycan be used in the following three scenarios to take advantage of theadditional available spectrum in either the licensed or unlicensed band:

In scenario (1) the unlicensed spectrum can be used with LTE-Atechnology which is called LTE in Unlicensed (LTE-U) or LicensedAssisted Access (LAA). LTE-U can extend the LTE technology intounlicensed deployments, enabling operators and vendors to leverageexisting or planned investments in LTE/evolved packet core (EPC)hardware in the radio and core network. LTE-U can also be considered aSupplemental Downlink Component Carrier (CC) in a LTE CarrierAggregation (CA) configuration. The use of LTE in the unlicensed bandcan be in co-existence of LTE with other incumbent technologies deployedin the unlicensed band. Due to multiple LTE operators using the sameunlicensed spectrum, self-coexistence among different LTE operators inthe same band can also be encountered.

In scenario (2) an opportunistic networking embodiment uses the LTElicensed band together with another Radio Access Technology (RAT) usedin high frequency spectrum, such as millimeter wave (mmWave). The optionto opportunistically use the mmWave channel cannot always be guaranteed,due to the potentially high path-loss and restrictive beam formingrequirements to achieve reasonable link/channel quality. A design thanincludes support opportunistic networking and use of mmWave (whenchannel condition is favorable) can be beneficial to ensure the basicquality of service (QoS), which can improve user experience. Celldensification can trigger interest in applying the mmWave spectrum atdensely populated areas in order to provide local coverage withoutcausing excessive inter-cell interference. Use of a highly directionalantenna array and beam forming with mmWave communication can provideadditional coverage and capacity improvements. In some embodiments, themmWave bands can be regarded as an additional secondary carrier andSCell in order to improve the existing LTE system performance.

In scenario (3) Device-to-Device (D2D) service can be used in unlicensedspectrum together with the conventional LTE service in licensedspectrum. The D2D service in unlicensed spectrum can be used toopportunistically off-load the traffic demand in licensed band LTEservice and improve the overall data rate and user experience.

The use of additional spectrum in the above examples can lead to thecoexistence of frequency bands with different propagationcharacteristics within the same system. A framework can be built on theconcept of an unconventional carrier type (UCT) concept together withthe operation of quickly turning the cell on/off to supportopportunistic networking options and address coexistence. Severalconcepts can be used in the design of opportunistic networking,including: (A) utilize a concept of licensed-assisted (LTE assisted)spectrum sharing scheme; (B) utilize a carrier aggregation concept and(C) utilize a fast cell on/off mechanism to support opportunistic use ofspectrum and networking.

These opportunistic networking concepts will be further explored in thedescription of the unconventional carrier type design heading. However,an introduction to a system that can use opportunistic networking isfirst described to aid in the comprehension of the design.

Wireless mobile communication technology uses various standards andprotocols to transmit data between a base station and a wireless mobiledevice. Wireless communication system standards and protocols caninclude the 3rd Generation Partnership Project (3GPP) long termevolution (LTE) standard; the Institute of Electrical and ElectronicsEngineers (IEEE) 802.16 standard, which is commonly known to industrygroups as worldwide interoperability for microwave access (WiMAX); andthe IEEE 802.11 standard, which is commonly known to industry groups asWi-Fi. Mobile broadband networks can include various high speed datatechnologies, such as 3GPP LTE systems. In 3GPP radio access networks(RANs) in LTE systems, the base station can include Evolved UniversalTerrestrial Radio Access Network (E-UTRAN) Node Bs (also commonlydenoted as evolved Node Bs, enhanced Node Bs, eNodeBs, or eNBs) and/orRadio Network Controllers (RNCs) in an E-UTRAN, which communicate with awireless communication device, known as user equipment (UE).

Turning to FIG. 1, an example of a portion of a radio access network(RAN) system 100 includes a single cellular air interface (such as anLTE/LTE-Advanced access link) being provided between an primary basestation 104 and a UE 102 (i.e., on Access Link A), and an air interface(a supplemental network interface such as a LTE-U based interface) beingprovided between a secondary base station 106 and the UE 102 (i.e., onAccess Link B). The UE 102 is located within a macro cell coverage 108.The UE 102 determines that connection with the secondary base station106 will be beneficial to a user of the UE 102. In some embodiments, theUE 102 retains Access Link A to the primary base station 104. The UE 102can offload some or part of wireless services onto Access Link A. Inother embodiments, the UE 102 disconnects from Access Link A and movesall wireless services to Access Link B. In some embodiments, Access LinkA and Access Link B use the same frequency and technology. In otherembodiments, Access Link A and Access Link B use different frequencies(e.g., LTE licensed frequencies and unlicensed frequencies) anddifferent link technology (e.g., LTE and Wi-Fi). In other embodiments,Access Link A and Access Link B use different frequencies and similarlink technology (e.g., LTE and LTE over mmWave).

FIG. 2 presents a chart 200 of different application scenarios 202 forUCT. A UCT carrier design provides a general framework to enable LTE tobe deployed in scenarios where existing LTE/LTE-A may not be suitable,while still meeting the above target requirements. Although anenhancement for unlicensed band deployment is an advantage for UCT, theUCT can be used in the licensed band as well. It can be used as DLsupplementary secondary carrier (DSC) or supporting both DL and UL. Itcan be supported in both frequency division duplexing (FDD) and timedivision duplexing (TDD) modes.

When used in a single carrier operation 204, the UCT can operate as astand-alone carrier either in a licensed or an unlicensed band (e.g., asprimary carrier).

An application of UCT can be (1) as a secondary carrier providing anSCell 212 on an unlicensed band in a carrier aggregation (CA) 206scenario, or (2) as a secondary carrier providing an SCell 224 in aMaster eNB (MeNB) group 218, or as a secondary carrier providing anSCell 232 in an SeNB group 220 in case of dual connectivity (DC) 208scenarios. In some embodiments of CA 206 (see also long term evolutionrelease 12 specification (LTE Rel-12)), the secondary carrier providingan SCell 212 is assumed to be synchronized with a primary cell providinga PCell 210. However, due to the use of UCT in the unlicensed band,additional CA 206 scenarios where the secondary carrier providing SCell212 is not synchronized with the primary cell providing PCell 210 can bedescribed in future LTE releases (LTE Rel-13 and beyond). In addition,UCT can also act as an supplementary primary carrier providing an sPCell230 in an SeNB group 220 in the DC 208.

The use of UCT as the primary carrier providing a PCell 210 in the CA206 scenario and/or as the primary carrier providing a PCell 222 in theMeNB group 218 in case of the dual connectivity 208 is also possible.

FIG. 3 is a schematic diagram 300 illustrating a long term evolution(LTE) communication frame 304 of a 10 ms duration 302. In oneembodiment, each frequency allocation (carrier) can be in 108 kHzincrements. In the diagram shown, a minimum of six carriers are shown.This allows for a bandwidth of 1.08 MHz (six carriers times 180 kHz=1.08MHz bandwidth). In some embodiments, the carriers can be expanded to 110blocks (110 carriers times 180 kHz=19.8 MHz). The frame 304 can be 10 mswith each slot 308 being 0.5 ms (and each subframe 306 being 1 ms).

The slot 308 at a carrier is a resource block 310, which includes sevensymbols at 12 orthogonal frequency-division multiplexing (OFDM)subcarriers. A resource element 312 is one OFDM subcarrier for theduration of one OFDM symbol. The resource block 310 can include 84resource elements 312 when using a normal cyclic prefix (CP). OFDMspacing between individual subcarriers in LTE can be 15 kHz. A guardperiod of a CP can be used in the time domain to help prevent multipathinter-symbol interference (ISI) between subcarriers. The CP can be aguard period before each OFDM symbol in each subcarrier to prevent ISI(such as due to multipath).

LTE frames can be altered for use with a UCT framework. FIGS. 4-11 showvarious embodiments in which an LTE frame is used with a UCT framework.FIG. 4 shows an alignment gap for synchronization with a primarycarrier. FIG. 5 shows channel reservation in conjunction with a UCT.FIG. 6 shows an extended subframe or super subframe used insynchronization. FIG. 7 shows a reduced length subframe for use withsynchronization. FIG. 8 shows an example of an unsynchronized frame withPSS/SSS transmissions. FIG. 9 shows an example of a synchronized framethat uses periodic transmission of discovery subframes and channelreservation. FIG. 10 shows an unsynchronized subframe with channelreservation. FIG. 11 shows an unsynchronized subframe with channelreservation and discovery subframes. These Figures will be described inconjunction with UCT design including UCT types and variations.Unconventional Carrier Type (UCT) design

Opportunistic networking utilizes one or multiple bands/channels thatare used or shared with other radio access technologies (RATs) such asWLAN and mmWave, while the conventional LTE (or simply referred to asLTE) uses one or multiple frequency bands that are exclusively assignedto LTE (such as LTE carrier aggregation or New Carrier Type (NCT). Anunconventional carrier type can support opportunistic networking inlicensed and/or unlicensed spectrum. In this description, such carrieris referred to as an unconventional carrier type (UCT), while referringto LTE in a licensed carrier as LCT (licensed carrier type).

In some embodiments, design objectives of UCT can include: (1)opportunistic use of additional available spectrum using LTE and otherRATs (e.g., WLAN, mmWave, etc.) (this can be considered as a spectrumsharing mechanism in conjunction with the use of LTE technology, e.g., alicensed-assisted (LTE assisted) spectrum sharing scheme); (2) efficientsharing of spectrum with other incumbent RATs in the additionalspectrum; (3) conforming to regulatory restrictions of additionalavailable spectrum for the licensed or unlicensed band; and (4) lowerinterference to other RATs or LTE in the same or an adjacent band.

Objective 1: Opportunistic Use of Additional Available Spectrum UsingLTE and other RATs such as WLAN, mmWave, etc.

Some challenges for RATs used in the high frequency band (e.g., mmWavecommunications) include large path loss (especially fornon-line-of-sight scenarios) and, signal blocking/absorption by variousobjects in the environment. Advanced antenna arrays with smart beamselection/tracking algorithms can be used to address the signalattenuation or path-loss issue. This can lead to a limited availabilityunder unfavorable channel condition on the high frequency (e.g., mmWave)band. Therefore, very fast cell switching or fast opportunistic use ofthe mmWave channel can be used in leverage of the additional mmWaveresource.

Objective 2: Efficient Sharing of Spectrum with other RATs in theAdditional Spectrum

Some embodiments aid efficient sharing of the unlicensed band throughthe operation by fast switching of the UCT on the unlicensed bandbetween two states: Dormant (or OFF) and active (or ON). The UCTsubframes during the dormant state can be referred to as dormant (OFF)subframes, whereas the UCT subframes during the active state can bereferred to as active (ON) subframes. UCT activities during the dormantand active states can be categorized into two separate tasks: design ofactive subframes and design of dormant subframes.

During the active state/subframes, the UCT may perform DL and/or UL LTEoperations, whereas during the dormant subframe, the UCT will refrainfrom transmission so as to reduce interference, thus enabling the use ofthe unlicensed band for other incumbent RATs. Therefore, the activestate/subframe and the dormant state/subframe can be regarded as the ONstate/subframe and the OFF state/subframe, respectively.

In one embodiment and when there is no LTE traffic, the UCT can be in adormant state, where all subframes are dormant subframes. While thestate is labeled as OFF or dormant, some signaling or control channelscan be transmitted on the UCT secondary carrier for special purposes(such as synchronization, signal strength/quality measurements, etc.)during this state. These subframes conveying these signal/channels arestill referred to as OFF subframes (or OFF state) since there are nodata (traffic) transmissions (e.g., physical downlink shared channel(PDSCHs)) in these subframes.

Objective 3: Conforming to the Regulatory Restrictions of the AdditionalAvailable Spectrum for the Licensed or Unlicensed Band

In order to follow restrictions (such as regulatory restrictions) of theunlicensed band, the OFF/dormant subframes can be used to performprotocols such as listen before transmit (LBT) to scan if the wirelessmedium (also known as wireless spectrum, wireless frequencies, channel,etc.) is busy or idle. Additionally, the UCT can also reserve the mediumfrom other RATs (such as by performing a spoofing mechanism to reservethe channel for its own transmission). Once the medium is reserved (orsensed idle in case the reservation is not required depending on the LBTprotocol), the UCT can transition from the OFF/dormant state to theON/active state, and the active subframe is used for transmitting data(e.g., PDSCH).

Objective 4: Lower Interference to other Radio Access Technologies (RAT)or LTE in the Same or Adjacent Band

In some embodiments and in order to aid in minimizing transmissionoverhead and in reducing interference, the UCT design can minimize theperiodic transmission of signals normally transmitted in LCT. Forexample and in DL LCT design, the following signals are transmittedperiodically in frequency division duplex (FDD) and time division duplex(TDD).

In some embodiments of FDD DL, several signals are transmittedperiodically. Cell-specific reference signal (CRS) is transmitted inevery subframe, except the physical downlink shared channel (PDSCH)portion of the multicast-broadcast single-frequency network (MBSFN)subframe. PSS and SSS are transmitted in subframes 0 and 5. Physicalbroadcast channel (PBCH) is transmitted in subframe 0. SIB-1 istransmitted in subframe 5 on the systems frame number (SFN) satisfyingthe condition, SFN mod 2=0 (i.e., every other frame). Paging insubframes 0, 4, 5 and 9 on frame satisfy the equation SFN mod T, where Tis the discontinuous reception (DRX) cycle of the UE.

In some embodiments of TDD DL, several signals are transmittedperiodically. CRS is transmitted in every downlink subframe, except thePDSCH portion of the MBSFN subframe. PSS are transmitted in subframes 0and 5. SSS are transmitted in subframes 1 and 6. PBCH is transmitted insubframe 0. SIB-1 is transmitted in subframe 5 on the SFN satisfying thecondition, SFN mod 2=0 (i.e., every other frame). Paging in subframes 0,1, 5 and 6 on frame satisfy the equation SFN mod T, where T is the DRXcycle of the UE.

In addition, CRS transmissions can be reduced. CRS transmission providesreference signal received power/reference signal received quality(RSRP/RSRQ) measurement, fine-frequency tracking and channel estimation.However, CRS transmission on empty subframes (e.g., in the OFF/dormantsubframe) can cause interference with other RATs and/or LTE-U systemsusing the spectrum. If a CRS transmission power exceeds a certainthreshold, the incumbent WLAN network can sense the medium as busy andrefrain from transmission. Reducing or removing the transmission of CRSon UCT can improve the efficiency of medium use by other RATs.

Reduced transmission of CRS can be achieved in several possible ways. Ina first embodiment, CRS transmission can be limited to active subframes.In dormant subframes, UCT can refrain from CRS transmission. In a secondembodiment, CRS is eliminated from both active and dormant subframes.Alternative signals (such as channel state information reference signal(CSI-RS), demodulation reference signal (DM-RS), etc.) can be used toperform these tasks of CRS, making CRS transmission potentiallyredundant. In a third embodiment, a cell on/off mechanism can beintroduced, whereby UCT will be switched off when not transmitting dataand turned on when there is data available to be transmitted.

In some embodiments, transmission frames can be synchronized. In someembodiments of LCT, PSS/SSS is used for initial coarse time andfrequency synchronization. In addition, PSS/SSS can also be used forcell selection purposes during initial access. Similar to transmissionof CRS, periodic transmission of PSS/SSS can introduce additionalinterference to the other RATs/LTE network in the unlicensed band. In anembodiment, whether PSS/SSS transmission is provided on UCT depends onthe geographical location and the spectrum location of a UCT secondarybase station with respect to a licensed primary base station. If boththe primary base station and secondary base station are co-located andthe secondary base station band is adjacent to the primary base station(i.e., inter-band CA), then the PSS/SSS transmitted on the primary basestation can be used for secondary base station synchronization. PSS/SSStransmission may be considered redundant on the secondary base station.In a second example where the secondary base station is not co-locatedwith the primary base station, or in case of intra-band CA, primary basestation synchronization may not be as effective when re-used for UCTsecondary base station synchronization purposes.

Several different design embodiments can be considered for thetransmission of such PSS/SSS signals. In a first embodiment, PSS/SSStransmission can be eliminated on the UCT secondary base station in caseof co-located inter-band CA as described above.

In a second embodiment, PSS/SSS can follow transmission timing as in anLCT primary carrier (e.g., in case of FDD, PSS and SSS can betransmitted in subframes 0 and 5 in a frame). Actual transmission can belimited to when the subframes 0 and 5 are active subframes. In case of adormant subframe, no PSS/SSS transmission will occur.

In a third embodiment, transmission of PSS/SSS can follow new timing,different from an LCT primary carrier. For example, transmission ofPSS/SSS can take place on a k-th active subframe in a frame on UCT(i.e., every k active subframe).

In a fourth embodiment and instead of transmitting legacy PSS/SSS forsynchronization purposes, a new synchronization or discovery signal canbe used. In addition, a new subframe structure can be designed to beused for transmitting only discovery signals (such as subframes thatinclude the discovery signal, which are called discovery subframes). Adiscovery signal can be transmitted during the OFF state, and thediscovery signal may be used for cell identification, radio resourcemanagement (RRM) measurements and other purposes.

In some embodiments, transmission of PBCH/paging and other systeminformation can be eliminated from a UCT secondary base station. Suchinformation can be carried out on licensed primary base stationcarriers. In case of stand-alone applications of a UCT, however, suchdiscovery signal may still be necessary. If a stand-alone UCT isoperated on an unlicensed band, then the legacy schemes may not bereadily applicable. Similar to the PSS/SSS mechanisms as describedabove, new timing can be defined for transmission of such signal on aUCT.

Using the description above, embodiments of a UCT system are describedbelow.

Type 1 UCT

In FIG. 4, an example of a type 1 UCT is shown. In this example, thesubframe/frame boundary of a UCT secondary eNB 404 is aligned with thesubframe/frame boundary of a legacy primary eNB 402. In this example, inthe OFF/dormant subframes 418, the UCT secondary eNB 404 refrains fromtransmission. Before the transition/switch to an active state, the UCTsecondary eNB 404 may perform LBT that can include a channel reservationmechanism with timing 412. Once the UCT secondary eNB 404 reserves themedium or senses the channel idle, the UCT secondary eNB 404 cantransmit data in active subframes 416, i.e., transition to the ON/activestate. In order to maintain alignment with the primary carrier 402subframes (406, 408 and 410), a portion of active states right beforethe first active subframe is left unused. This gap is referred to as analignment gap 414.

In some embodiments and during the alignment gap 414, if no signal istransmitted by LAA eNB or UE, then other incumbent RATs (e.g., WLAN) aswell as other LAA operators may determine the medium is empty due tolack of transmission. The incumbent RATs or LAA operators may attempt totransmit during an empty medium. To keep the medium reserved fortransmission in the first active subframe, the LAA eNB or UE cantransmit a signal to keep the medium occupied until the first subframe.Several mechanisms can be used to address this issue of mediumreservation.

In FIG. 5, a chart 500 shows a mechanism for channel reservation thatcan be used during an alignment gap 502. A signal (shown here as WLANpreambles 504 and 506) can be transmitted during the alignment gap 502to keep the medium busy before transmission of a subframe 508. In theembodiment shown in FIG. 5, the signals transmitted are the 802.11 apreamble signals consisting of Bus long STF (short training field), BusLTF (long training field) and 4us long signal field, a total duration of20us. Multiple copies of the signal can be transmitted during analignment gap to keep the medium occupied. Other alternative signals canalso be considered. In different embodiments, the signal can take theform of a noise signal (e.g. white noise, pseudo-random sequence etc.),empty (if less than a duration of time), a reservation message and/or adiscovery signal. In a first example embodiment, a form of a noisesignal (such as pseudo-random noise sequence) can be broadcastthroughout the entire transmission bandwidth. In a second embodiment andif the alignment gap is less than a certain duration, then the alignmentgap can be left empty 510. A WLAN access point/station (AP/STA) canwait/scan a duration of at least short interframe space (SIFS), packetcoordination function (PCF) interframe space (PIFS) or distributedcoordination function (DCF) interframe space (DIFS) before transmittingacknowledge (ACK) info, beacon and data frame respectively. If thealignment gap is less than one of these values (e.g., less than SIFS)then the alignment gap can be left empty.

In a third example, the secondary base station can transmit some form ofa signal that is understood by WLAN (e.g., physical(PHY) layer spoofingsignal based on WLAN preambles 504 and 506, RTS message or CTS message,etc.). In FIG. 5, one example of transmitting WLAN preambles 504 and 506is shown. In the embodiment shown an alignment gap is 50 microseconds(us). An LTE symbol duration without CP is 66.7 us, which is larger thanthe alignment gap of 50 us. Instead, transmission of the short trainingfield (STF), long training field (LTF) and signal field (SIG) are partof a WLAN preamble that causes WLAN devices to see the medium as busy.As an added benefit, a WLAN AP/STA can decode the SIG portion of thesignal and update their network allocation vector (NAV) for the durationspecified in the preambles 504 and 506. One or more copies of areservation message can be transmitted. Since a WLAN AP/STA wait/scans aduration of at least SIFS, PIFS or DIFS before transmitting ACK info,beacon and data frame respectively, if the remaining alignment gap 510after transmitting one or more such preambles 504 and 506 is less thanthat the duration, then the additional gap 510 can be left empty. Insome embodiments, a clear to send (CTS) message, request to send (RTS)message or RTS-CTS message can also be used in place of the preamble(s)504 and 506.

In a fourth example and if the duration is more than a LTE symbollength, then an LTE discovery signal can be transmitted. Depending onthe duration, one or more symbols of an LTE signal can be transmitted.Some example of discovery signals include PSS/SSS, one or severalsymbols of CRS, CSI-RS, SRS, DMRS, PRS, etc. or an enhanced version ofthese signals.

This alignment gap can be larger than one subframe. During the gap, UEscheduling (including the selection of the target UE, modulation andcoding scheme (MCS), resource block (RB) allocation, etc.) and encoding(e.g., PDSCHs) can be performed at the eNB.

In FIG. 6, a second mechanism 600 is shown, which can be used forchannel reservation. A primary eNB 602 transmits data over frames 606,608 and 610. A UCT secondary eNB 604 is scheduled to transmit dataduring active subframes 616 and to transition to a dormant state duringdormant subframes 618. To synchronize transmission of the primary eNB602 and secondary eNB 604, a LBT protocol and/or reservation mechanism612 can be used to reserve the channel. An alignment gap after themechanism 612 is merged with a first active subframe to create asuper-subframe 614. Alternatively, the alignment gap can be used totransmit discovery signals as mentioned above.

In another embodiment shown in FIG. 7, a discovery subframe 714 istransmitted after a channel reservation 712 is performed. As describedearlier, the discovery subframe 714 can contain signals forsynchronization and RSRP measurement. To accommodate the discoverysubframe 714, a first active subframe immediately following thediscovery subframe 714 can be shortened to a reduced length subframe720. For example, a primary eNB 702 transmits data over frames 706, 708and 710. A UCT secondary eNB 704 is scheduled to transmit data duringactive subframes 716 and to transition to a dormant state during dormantsubframes 718. To synchronize transmission of the primary eNB 702 andsecondary eNB 704, a LBT protocol and/or reservation mechanism 712 canbe used to reserve the channel. A discovery subframe 714 is transmittedafter the LBT/reservation mechanism 712. A first active subframe isshortened to create the reduced length subframe 720.

In FIG. 8, a legacy PSS/SSS 808 can be used as a discovery signal. Thelegacy PSS/SSS 808 signal can be considered as a special case ofdiscovery signal. If the PSS/SSS 808 is transmitted, then additionaldiscovery subframes may not be required. Instead the existing subframe(shown as subframe 0) can accommodate such a signal. One such example ispresented in FIG. 8. Here, the PSS/SSS signal 808 is transmitted in thefirst subframe (i.e., subframe 0). For example, the UCT can perform anLBT and channel reservation 806 before transitioning to an active state.During the active subframes 810, the PSS/SSS signal 808 is transmitted.After transmission of the active subframes 810, the UCT transitions to adormant state 812.

In FIG. 9, another embodiment of type 1 UCT frames is shown in which adiscovery subframe 914 is periodically transmitted in both dormantsubframes 918 and active subframes 916. The transmission of thediscovery subframe 914 in this example is not preceded by an LBT orchannel reservation mechanism. The UCT transmits the discovery subframe914 (or signal) whether or not the medium is busy. In anotherembodiment, the transmission of each discovery subframe 914 can bepreceded by an LBT scheme. To aid in LBT, a transmission power of thediscovery subframe 914 can be limited, in accordance with a regulatoryrequirement. For example, the UCT can perform LBT and channelreservation 912 before transitioning to an active state (which mayinclude an alignment gap 922). During the active subframes 916, thediscovery subframe 914 is transmitted. This can cause a subframe tobecome a reduced length subframe 920. After transmission of the activesubframes 916, the UCT transitions to a dormant state with dormantsubframes 918. A discovery subframe 914 can be sent during the dormantsubframe 918 with or without using LBT.

Type 2 UCT

In FIG. 10, an embodiment 1000 of a type 2 UCT is shown in primary eNB1002 subframes 1006, 1008 and 1010, and UCT secondary eNB 1004 subframes1016 are not synchronized (or aligned). In this example, thesubframe/frame boundary of the UCT secondary eNB 1004 is not alignedwith the subframe/frame boundary of the legacy primary eNB 1002. Duringa dormant state 1018, the UCT refrains from transmission. In order tomove to an active state, the UCT performs an LBT and channel reservationmechanism 1012. Since alignment between the primary eNB subframeboundary and secondary eNB subframe boundary is not required for type 2UCT, unlike the type 1 UCT, no alignment gap is defined. Once the mediumis reserved, LAA can start transmission. The active subframes 1016 in atype 2 UCT are not aligned with the corresponding primary eNB subframes1006, 1008 or 1010.

In another embodiment 1100 of a type 2 UCT shown in FIG. 11, a discoverysubframe 1114 can be transmitted after an LBT and channel reservationprotocol 1112 before the first active subframe in active subframes 1116.For example, the UCT can perform the LBT and channel reservation 1112and send the discovery subframe 1114 before transitioning to an activestate. During the active subframes 1116, data is transmitted (whichincludes sending and/or receiving). After transmission of the activesubframes 1116, the UCT transitions to a dormant state with dormantsubframes 1118. The discovery subframe 1114 can be sent during thedormant subframe 1118 with or without using LBT.

Alternatively, a discovery signal similar to PSS/SSS can be transmittedin the first subframe similar to FIG. 8 instead of before the firstsubframe.

FIG. 12 shows an embodiment of a method 1200 of LTE transmissions in anunlicensed band in accordance with the present invention. In thisembodiment, LTE-U transmissions can be based on the followingoperations. It should be noted that some of the operations can beomitted in some deployment scenarios. The method 1200 can beaccomplished by a system 100 such as shown in FIG. 1, including primarybase station 104, secondary base station 106 and UE 102.

In this embodiment, there are a PCell 1202, two UCT secondary basestations 1204 and 1206, and a UE 1208. However, it should be noted thatthe system can include more computing resources than shown (e.g., the UE1208 is one UE of many UEs connected to the primary base station 1202,the UCT secondary base stations 1204 and 1206 are two of many secondarybase stations that serve the UEs). Each secondary base station 1204 and1206 transmits discovery signals 1210 in ON subframes or OFF subframes.

The UE 1208 then optionally reports 1214 the measurement results 1212 tothe primary base station 1202, e.g., through a licensed band. Themeasurement reports 1214 can include RSRP/RSRQ and other interferenceconditions for each secondary base station 1204 and 1206. Each secondarybase station 1204 and 1206 can also optionally measure interferencepower and report 1216 to the primary base station 1202.

The primary base station 1202 selects one or multiple bands/channels tobe used for PDSCH transmissions, e.g., based on the measurement reportsfrom one or multiple UEs and/or from the secondary base stations. Thebands/channels selection can be UE-specific, a group of UE-specific, orprimary base station-specific. Once one or more bands/channels areselected, the bands/channels selection information can be sent 1220 tothe UE(s) 1208 (e.g., through licensed bands using one or multiple ofphysical broadcast channel (PBCH), physical downlink control channel(PDCCH), enhanced physical downlink control channel (ePDCCH), andPDSCH).

The selected secondary base station may transmit reference signals 1222(such as CSI-RS) that can be used for CSI feedback by UE 1208. TheCSI-RS transmission can be preceded by an LBT or can be simplytransmitted using a predetermined set of resources. Then, UE 1208reports 1224 to the primary base station 1202 CSI (e.g., rank indicator(RI), precoding matrix indicator (PMI), and channel quality indicators(CQIs)) for all or a part of the selected secondary base station(s) 1204and 1206 (in this case, it is secondary base station 2 (1206)). In anembodiment, the CSI can be measured based on the discovery signals 1210.

The primary base station 1202 schedules 1226 PDSCH transmission of eachselected secondary base station 1206 based on the measurement reportsand CSI reports from the UE 1208 (often multiple UEs at once). Thescheduling for each secondary base station 1204 and 1206 may includedecision on Tx power, target UE, amount of resources (i.e., number ofRBs), data rate (modulation and coding scheme), rank, precoding matrix,etc. The secondary base station 1204 and 1206 scheduling by the primarybase station 1202 is referred to as cross-carrier scheduling.

When a particular subframe of an secondary base station 1206 isscheduled (i.e., the secondary base station 1206 transmits one or morePDSCHs in the particular subframe), the secondary base station 1206transitions 1228 from an OFF state to an ON state (i.e., the secondarybase station 1206 is turned on) and transmits a PDSCH(s) 1232. At thesame subframe (or at a predefined time instance), the primary basestation 1202 transmits a PDCCH(s) 1230 to each target UE (such as the UE1208) that conveys at least UE identification, secondary base stationidentification (indicating which secondary base station 1206 transmitsthe PDSCH 1232 and other information needed for PDCSH decoding). EachPDCCH 1230 transmitted by the primary base station 1202 is associatedwith the PDSCH 1232 transmitted by the secondary base station 1206. ThePDSCH 1232 transmitted by the secondary base station 1206 can bepreceded by an LBT (and/or a channel reservation).

After transmission of the PDSCH 1232 to the UE 1208, the UE 1208 canreport the PDSCH 1232 transmission to the primary base station 1202through a hybrid automatic repeat request (HARD) report 1234. If no moredata is scheduled, then the secondary base station 1206 can turn off1236).

If the secondary base station 1204 is not scheduled, i.e., no PDSCH istransmitted, the secondary base station 1204 stays in an OFF state (ortransitions from an ON state to an OFF state). The transition betweenON/OFF states within the UCT secondary base station 1204 can be on asubframe basis or on a group of subframes basis.

A discovery signal can be one or a combination of various signals in LTE(e.g., PSS, SSS, CRS, CSI-RS, etc.), which may include modifications tothese signals. The discovery signal transmissions 1210 can be periodicor aperiodic. In case of being aperiodic, the discovery signaltransmission 1210 can be preceded by an LBT scheme which may include thechannel reservation for the discovery signal transmission 1210. Inanother embodiment, the discovery signals 1210 can be transmittedwithout sensing the channel, i.e., they can be transmitted regardless ofongoing transmissions of other RATs or LTE-U transmissions by otheroperators. The UE 1208 can obtain at least coarse frequency/timesynchronization using the discovery signals 1210 (or subframes). The UE1208 can use the discovery signals 1210 to measure the quality of UCTsignals such as RSRP/RSRQ. The UE 1208 can also measure interferencepower using the discovery signal 1210 (or other schemes, e.g., totalreceived power).

Principles of the above embodiment can also be applied to supportopportunistic networking of high frequency (e.g., mmWave) communicationwith the following four operations.

(1) A UCT transmits discovery signals (or discovery subframes orsynchronization) on the mmWave spectrum. The discovery signaltransmissions can be periodic or aperiodic. In case of aperiodictransmissions of discovery signals, a UE can obtain at least coarsefrequency/time synchronization using the discover signals (orsubframes). The UE can optionally use the discovery signals to measurethe quality of UCT signals such as RSRP/RSRQ. The UE can also measureinterference power using the discovery signals (or other schemes such astotal received power, etc.).

(2) A UE then reports measurements to the primary base station (e.g.,through a licensed band). The measurement report can include RSRP/RSRQand other interference conditions.

(3) The primary base station selects one or multiple bands/channels tobe used for PDSCH transmissions (e.g., based on the measurement reportsfrom one or multiple UEs or other information related to the mmWave beamforming). If channel conditions are favorable, one or morebands/channels can be selected for opportunistic data transmission inthe mmWave spectrum.

(4) The primary base station turns on the secondary base station andschedules PDSCH transmissions on the secondary base station UCT to oneor multiple UEs (e.g., via cross-carrier scheduling). The scheduling mayalso be done in the secondary base station (self-scheduling ornon-cross-carrier scheduling). In one embodiment, the scheduling is onlydone in the secondary base station if the control channel or schedulingcan be transmitted reliably in the secondary base station.

While UEs, primary base stations, secondary base stations and othersystems have been discussed in the singular for ease of understanding,it should be recognized that embodiments may include multiples of thesesystems and operate in parallel fashion (such as scheduling multiple UEsfor transmission timing).

FIG. 13 is an example illustration of a mobile device, such as a UE, amobile station (MS), a mobile wireless device, a mobile communicationdevice, a tablet, a handset, or another type of mobile wireless device.The mobile device can include one or more antennas configured tocommunicate with a transmission station, such as a base station (BS), aneNB, a base band unit (BBU), a remote radio head (RRH), a remote radioequipment (RRE), a relay station (RS), a radio equipment (RE), oranother type of wireless wide area network (WWAN) access point. Themobile device can be configured to communicate using at least onewireless communication standard including 3GPP LTE, WiMAX, HSPA,Bluetooth, and Wi-Fi. The mobile device can communicate using separateantennas for each wireless communication standard or shared antennas formultiple wireless communication standards. The mobile device cancommunicate in a WLAN, a wireless personal area network (WPAN), and/or aWWAN.

FIG. 13 also provides an illustration of a microphone and one or morespeakers that can be used for audio input and output from the mobiledevice. The display screen can be a liquid crystal display (LCD) screenor other type of display screen, such as an organic light emitting diode(OLED) display. The display screen can be configured as a touch screen.The touch screen can use capacitive, resistive, or another type of touchscreen technology. An application processor and a graphics processor canbe coupled to internal memory to provide processing and displaycapabilities. A non-volatile memory port can also be used to providedata input/output options to a user. The non-volatile memory port canalso be used to expand the memory capabilities of the mobile device. Akeyboard can be integrated with the mobile device or wirelesslyconnected to the mobile device to provide additional user input. Avirtual keyboard can also be provided using the touch screen.

Many of the systems described include computing resources and systems. Acomputing system can be viewed as an information passing bus thatconnects various components. A computing system includes a processorhaving logic for processing instructions. Instructions can be stored inand/or retrieved from memory and a storage device that includes acomputer-readable storage medium. Instructions and/or data can arrivefrom a network interface that can include wired or wirelesscapabilities. Instructions and/or data can also come from an I/Ointerface that can include such things as expansion cards, secondarybuses (e.g., USB, etc.), devices, etc. A user can interact with thecomputing system through user interface devices and a rendering systemthat allows the computer to receive and provide feedback to the user.

Embodiments and implementations of the systems and methods describedherein may include various operations, which may be embodied inmachine-executable instructions to be executed by a computer system. Acomputer system may include one or more general-purpose orspecial-purpose computers (or other electronic devices). The computersystem may include hardware components that include specific logic forperforming the operations or may include a combination of hardware,software, and/or firmware.

Computer systems and the computers in a computer system may be connectedvia a network. Suitable networks for configuration and/or use asdescribed herein include one or more local area networks, wide areanetworks, metropolitan area networks, and/or Internet or IP networks,such as the World Wide Web, a private Internet, a secure Internet, avalue-added network, a virtual private network, an extranet, anintranet, or even stand-alone machines which communicate with othermachines by physical transport of media. In particular, a suitablenetwork may be formed from parts or entireties of two or more othernetworks, including networks using disparate hardware and networkcommunication technologies.

One suitable network includes a server and one or more clients; othersuitable networks may contain other combinations of servers, clients,and/or peer-to-peer nodes, and a given computer system may function bothas a client and as a server. Each network includes at least twocomputers or computer systems, such as the server and/or clients. Acomputer system may include a workstation, laptop computer,disconnectable mobile computer, server, mainframe, cluster, so-called“network computer” or “thin client,” tablet, smart phone, personaldigital assistant or other hand-held computing device, “smart” consumerelectronics device or appliance, medical device, or a combinationthereof.

Suitable networks may include communications or networking software,such as the software available from Novell®, Microsoft®, and othervendors, and may operate using TCP/IP, SPX, IPX, and other protocolsover twisted pair, coaxial, or optical fiber cables, telephone lines,radio waves, satellites, microwave relays, modulated AC power lines,physical media transfer, and/or other data transmission “wires” known tothose of skill in the art. The network may encompass smaller networksand/or be connectable to other networks through a gateway or similarmechanism.

Various techniques, or certain aspects or portions thereof, may take theform of program code (i.e., instructions) embodied in tangible media,such as floppy diskettes, CD-ROMs, hard drives, magnetic or opticalcards, solid-state memory devices, a nontransitory computer-readablestorage medium, or any other machine-readable storage medium wherein,when the program code is loaded into and executed by a machine, such asa computer, the machine becomes an apparatus for practicing the varioustechniques. In the case of program code execution on programmablecomputers, the computing device may include a processor, a storagemedium readable by the processor (including volatile and nonvolatilememory and/or storage elements), at least one input device, and at leastone output device. The volatile and nonvolatile memory and/or storageelements may be a RAM, an EPROM, a flash drive, an optical drive, amagnetic hard drive, or other medium for storing electronic data. TheeNB (or other base station) and UE (or other mobile station) may alsoinclude a transceiver component, a counter component, a processingcomponent, and/or a clock component or timer component. One or moreprograms that may implement or utilize the various techniques describedherein may use an application programming interface (API), reusablecontrols, and the like. Such programs may be implemented in a high-levelprocedural or an object-oriented programming language to communicatewith a computer system. However, the program(s) may be implemented inassembly or machine language, if desired. In any case, the language maybe a compiled or interpreted language, and combined with hardwareimplementations.

Each computer system includes one or more processors and/or memory;computer systems may also include various input devices and/or outputdevices. The processor may include a general purpose device, such as anIntel®, AMD®, or other “off-the-shelf” microprocessor. The processor mayinclude a special purpose processing device, such as ASIC, SoC, SiP,FPGA, PAL, PLA, FPLA, PLD, or other customized or programmable device.The memory may include static RAM, dynamic RAM, flash memory, one ormore flip-flops, ROM, CD-ROM, DVD, disk, tape, or magnetic, optical, orother computer storage medium. The input device(s) may include akeyboard, mouse, touch screen, light pen, tablet, microphone, sensor, orother hardware with accompanying firmware and/or software. The outputdevice(s) may include a monitor or other display, printer, speech ortext synthesizer, switch, signal line, or other hardware withaccompanying firmware and/or software.

It should be understood that many of the functional units described inthis specification may be implemented as one or more components, whichis a term used to more particularly emphasize their implementationindependence. For example, a component may be implemented as a hardwarecircuit comprising custom very large scale integration (VLSI) circuitsor gate arrays, or off-the-shelf semiconductors such as logic chips,transistors, or other discrete components. A component may also beimplemented in programmable hardware devices such as field programmablegate arrays, programmable array logic, programmable logic devices, orthe like.

Components may also be implemented in software for execution by varioustypes of processors. An identified component of executable code may, forinstance, comprise one or more physical or logical blocks of computerinstructions, which may, for instance, be organized as an object, aprocedure, or a function. Nevertheless, the executables of an identifiedcomponent need not be physically located together, but may comprisedisparate instructions stored in different locations that, when joinedlogically together, comprise the component and achieve the statedpurpose for the component.

Indeed, a component of executable code may be a single instruction, ormany instructions, and may even be distributed over several differentcode segments, among different programs, and across several memorydevices. Similarly, operational data may be identified and illustratedherein within components, and may be embodied in any suitable form andorganized within any suitable type of data structure. The operationaldata may be collected as a single data set, or may be distributed overdifferent locations including over different storage devices, and mayexist, at least partially, merely as electronic signals on a system ornetwork. The components may be passive or active, including agentsoperable to perform desired functions.

Several aspects of the embodiments described will be illustrated assoftware modules or components. As used herein, a software module orcomponent may include any type of computer instruction orcomputer-executable code located within a memory device. A softwaremodule may, for instance, include one or more physical or logical blocksof computer instructions, which may be organized as a routine, program,object, component, data structure, etc., that perform one or more tasksor implement particular data types. It is appreciated that a softwaremodule may be implemented in hardware and/or firmware instead of or inaddition to software. One or more of the functional modules describedherein may be separated into sub-modules and/or combined into a singleor smaller number of modules.

In certain embodiments, a particular software module may includedisparate instructions stored in different locations of a memory device,different memory devices, or different computers, which togetherimplement the described functionality of the module. Indeed, a modulemay include a single instruction or many instructions, and may bedistributed over several different code segments, among differentprograms, and across several memory devices. Some embodiments may bepracticed in a distributed computing environment where tasks areperformed by a remote processing device linked through a communicationsnetwork. In a distributed computing environment, software modules may belocated in local and/or remote memory storage devices. In addition, databeing tied or rendered together in a database record may be resident inthe same memory device, or across several memory devices, and may belinked together in fields of a record in a database across a network.

Reference throughout this specification to “an example” means that aparticular feature, structure, or characteristic described in connectionwith the example is included in at least one embodiment of the presentinvention. Thus, appearances of the phrase “in an example” in variousplaces throughout this specification are not necessarily all referringto the same embodiment.

As used herein, a plurality of items, structural elements, compositionalelements, and/or materials may be presented in a common list forconvenience. However, these lists should be construed as though eachmember of the list is individually identified as a separate and uniquemember. Thus, no individual member of such list should be construed as ade facto equivalent of any other member of the same list solely based onits presentation in a common group without indications to the contrary.In addition, various embodiments and examples of the present inventionmay be referred to herein along with alternatives for the variouscomponents thereof. It is understood that such embodiments, examples,and alternatives are not to be construed as de facto equivalents of oneanother, but are to be considered as separate and autonomousrepresentations of the present invention.

Furthermore, the described features, structures, or characteristics maybe combined in any suitable manner in one or more embodiments. In thefollowing description, numerous specific details are provided, such asexamples of materials, frequencies, sizes, lengths, widths, shapes,etc., to provide a thorough understanding of embodiments of theinvention. One skilled in the relevant art will recognize, however, thatthe invention may be practiced without one or more of the specificdetails, or with other methods, components, materials, etc. In otherinstances, well-known structures, materials, or operations are not shownor described in detail to avoid obscuring aspects of the invention.

Although the foregoing has been described in some detail for purposes ofclarity, it will be apparent that certain changes and modifications maybe made without departing from the principles thereof. It should benoted that there are many alternative ways of implementing both theprocesses and apparatuses described herein. Accordingly, the presentembodiments are to be considered illustrative and not restrictive, andthe invention is not to be limited to the details given herein, but maybe modified within the scope and equivalents of the appended claims.

Those having skill in the art will appreciate that many changes may bemade to the details of the above-described embodiments without departingfrom the underlying principles of the invention. The scope of thepresent invention should, therefore, be determined only by the followingclaims.

EXAMPLES

The following examples pertain to further embodiments.

Example 1 is a primary base station for cross-carrier scheduling that isconfigured to select a secondary base station for cross-carrierscheduling for communication with a mobile device over a set offrequencies shared with another radio access technology (RAT). Theprimary base station is further configured to send a request forcross-carrier scheduling to the secondary base station. The primary basestation is also configured to provide the secondary base station with aschedule for transmitting data to a mobile device. The primary basestation is further configured to cause the secondary base station totransmit the data in a portion of a second frame that aligns with afirst frame of the primary base station.

In Example 2, the primary base station of Example 1 can optionally beconfigured to receive a transmission quality report from user equipment(UE) that describes transmission quality measurements between the UE andthe secondary base station.

In Example 3, the primary base station of Examples 1-2 can optionally beconfigured to receive a transmission quality report from the secondarybase station that describes transmission quality measurements betweenthe secondary base station and a user equipment (UE).

In Example 4, the primary base stations in Example 1-3 can optionally beconfigured to receive a report indicating receipt of the data by a userequipment (UE) from the secondary base station.

In Example 5, the report of Example 4 can optionally be a hybridautomatic repeat request (HARQ) message.

Example 6 is an enhanced node B (eNB) for cross-carrier transmissioncomprising a first network interface, a second network interface and aprocessor. The first network interface is configured for communicatingwith a user equipment (UE) over a first set of wireless spectrum. Thesecond network interface configured for communicating with networkinfrastructure that includes an unconventional carrier type (UCT). Theprocessor is configured to receive a report from the UE including ameasurement of a UCT discovery signal sent from the UCT over a secondset of wireless spectrum. The processor is further configured to selectthe UCT for transmission of data to the UE and schedule transmission ofthe data over the UCT.

In Example 7, the UCT of Example 6 can optionally provide the physicaldownlink control channel (PDCCH) to the UE.

In Example 8, the eNB of Example 6 can optionally provide the physicaldownlink control channel (PDCCH) to the UE.

In Example 9, the eNB of Examples 6-8 can optionally include receivingthe report from the UE including the measurement of a periodic UCTdiscovery signal from the UCT.

In Example 10, the UE of Examples 6-8 can optionally be configured toreceive the report from the UE including the measurement of an aperiodicUCT discovery signal from the UCT.

Example 11 is a method of transmitting data comprising providing aprimary medium of communication with a user equipment (UE) using a firstband of frequencies. The method can further include receiving a reportdescribing transmission quality of a secondary base station with the UEover a secondary medium using a second band of frequencies shared withat least one radio access technology (RAT). The method can also furtherinclude selecting the secondary base station for use in cross-carriertransmission with the UE. The method can also include reserving thesecondary medium for communication with the UE. The method can furtherinclude scheduling a set of data for transmission over the secondarymedium by the secondary base station to the UE. The method can includecausing at least a subset of the set of data to be transmitted over thesecondary medium using a third generation partnership project (3GPP)compatible protocol.

In Example 12, the method of Example 11 can optionally includeperforming a listen before talk protocol.

In Example 13, the method of Examples 11-12 can optionally use anunlicensed set of frequencies as the secondary medium.

In Example 14, the method of Examples 11-12 can optionally use anunlicensed set of frequencies as the secondary medium.

In Example 15, the method of Example 14 can optionally includetransmitting a control channel scheduling the set of data over theprimary medium.

In Example 16, the method of Examples 11 can optionally includeperforming a listen before talk protocol; transmitting a control channelscheduling the set of data over the primary medium; transmitting achannel reservation signal over the secondary medium to reserve thesecondary medium; transmitting the subset of the set of dataasynchronously over the secondary medium as compared with the primarymedium; aligning subframes of the secondary medium with subframes of theprimary medium; using an unlicensed set of frequencies as the secondarymedium; or using a licensed set of frequencies as the secondary medium.

In Example 17, the method of Example 11 can optionally include aligningsubframes of the secondary medium with subframes of the primary medium.

In Example 18, the method of Example 17 can optionally transmitting achannel reservation signal over the secondary medium to reserve thesecondary medium.

In Example 19, the method of Example 18 further includes forming analignment gap between the channel reservation signal sent over thesecondary medium and an aligned subframe of the secondary medium.

In Example 20, the method of Example 19 can optionally includetransmitting at least a portion of a wireless local area network (WLAN)preamble during at least a portion of the alignment gap.

In Example 21, the method of Example 19 can optionally includetransmitting at least a noise signal during at least a portion of thealignment gap.

In Example 22, the method of Examples 19 is optionally transmitting atleast a portion of a discovery signal during at least a portion of thealignment gap.

In Example 23, the method of Examples 19 can optionally determining thata duration of the alignment gap is less than a threshold amount andrefraining from transmission during the alignment gap.

In Example 24, the method of Example 19 can optionally include one ormore of transmitting at least a portion of a wireless local area network(WLAN) preamble during at least a portion of the alignment gap;transmitting at least a noise signal during at least a portion of thealignment gap; transmitting at least a portion of a discovery signalduring at least a portion of the alignment gap; or determining that aduration of the alignment gap is less than a threshold amount andrefraining from transmission during the alignment gap.

In Example 25, the method of Example 17 can include forming a supersubframe that includes an alignment gap.

In Example 26, the method of Example 17 can optionally include forming areduced length subframe for transmission over the secondary medium.

In Example 27, the method of Example 11 can optionally transmitting thesubset of the set of data asynchronously over the secondary medium ascompared with the primary medium.

Example 28 is an comprising means to perform a method as described inany of claims 11-27.

Example 29 is machine readable storage including machine-readableinstructions that when executed implement a method or realize anapparatus as claimed in any of claims 11-27.

1. An apparatus of a user equipment (UE), comprising: memory for storinga licensed assisted access (LAA) subframe; a processor configured to:decode, from a radio access network (RAN) node, the LAA subframe togenerate decoded LAA subframe data; identify a primary synchronizationsignal (PSS), secondary synchronization signal (SSS) and cell-specificreference signal (CRS) within the decoded LAA subframe data; anddetermine that a discovery signal exists within the LAA subframe basedat least in part on identifying the PSS, SSS and CRS within the decodedLAA subframe data.
 2. The apparatus of claim 1, wherein the UE isconfigured to add the RAN node as a secondary cell.
 3. The apparatus ofclaim 1, further comprising a first wireless interface coupled to atransceiver configured to communicate using LAA using a secondary celloperation.
 4. The apparatus of claim 3, further comprising a secondwireless interface configured to communicate using long term evolution(LTE) using a primary cell operation.
 5. The apparatus of claim 1,wherein the processor is further configured to perform secondary celloperations using LAA.
 6. The apparatus of claim 1, further comprising afirst wireless interface coupled to a first transmitter using anunlicensed band with LAA in a secondary cell operation.
 7. The apparatusof claim 6, further comprising a second wireless interface coupled to asecond transmitter using an licensed band with using long term evolution(LTE) in a primary cell operation.
 8. The apparatus of claim 1, whereinthe processor is a baseband processor.
 9. An apparatus of a radio accessnetwork (RAN) node, comprising: a first wireless interface coupled to atransmitter using a licensed assisted access (LAA) band; a processorconfigured to: select a first subframe for discovery measurement timingfor a LAA discovery signal, wherein the first subframe contains aprimary synchronization signal (PSS), secondary synchronization signal(SSS) and cell-specific reference signals (CRS); generate a periodic LAAdiscovery signal based at least in part on the discovery measurementtiming and the first subframe; and provide the periodic LAA discoverysignal for transmission using the first wireless interface.
 10. Theapparatus of claim 9, wherein to provide the periodic LAA discoverysignal for transmission using the first wireless interface furthercomprises to provide the periodic LAA discovery signal for transmissionusing the first wireless interface when a transmission subframe isactive.
 11. The apparatus of claim 9, further comprising a secondwireless interface configured as a primary cell interface.
 12. Theapparatus of claim 11, wherein the LAA band is an unlicensed band. 13.The apparatus of claim 11, wherein the second wireless interface is along term evolution (LTE) interface.
 14. The apparatus of claim 9,wherein the first wireless interface is configured to transmit on a bandthat includes WLAN.
 15. The apparatus of claim 9, wherein the firstwireless interface is configured as an LAA secondary cell interface. 16.The system apparatus of claim 9, wherein the processor is a basebandprocessor.
 17. A computer program product comprising a computer-readablestorage medium that stores instructions for execution by a processor toperform operations of a radio access network (RAN) node, the operations,when executed by the processor, to perform a method, the methodcomprising: selecting a first occurring subframe of a discovery signalperiod for a licensed assisted access (LAA) discovery signal; generatinga non-empty subframe including the LAA discovery signal, a primarysynchronization signal and a secondary synchronization signal; andencoding the non-empty subframe for transmission at a time of the firstoccurring subframe of the discovery signal period.
 18. The computerprogram product of claim 17, wherein the LAA discovery signal isperiodic based on the discovery signal period.
 19. The computer programproduct of claim 17, wherein the non-empty subframe further comprises acell specific reference signal (CRS).
 20. The computer program productof claim 17, wherein the method further comprises providing a secondarycell to a user equipment (UE) using LAA.